1. Field of the Invention
The present invention relates generally to venting fuel tanks and more specifically to a fuel tank venting system, which may be located in a fuel cap or in a wall of the fuel tank.
2. Discussion of the Prior Art
Fuel tanks used with small engines usually allow fuel vapors to continually vent to the atmosphere. Sometimes check valves are incorporated in the gas cap to prevent the escape of fuel vapors. Some types of check valves seal well under high pressure, but allow fuel vapor seepage under low pressure. With marine fuel tanks, a thumb screw in the fuel cap is used to seal the marine fuel tank, when not in use. The thumb screw is opened in most cases to run the engine. During the time when the engine is running, fuel vapors are vented to the atmosphere. Some users may never tighten the thumb screw for the sake of convenience, allowing the escape of fuel vapors from the marine fuel tank, at all times.
Accordingly, there is a clearly felt need in the art for a fuel tank venting system to prevent fuel vapors from being vented to the atmosphere, while allowing atmospheric air to enter the fuel tank for the purpose of fuel flow.